This essay was published in 1763 and belongs to the works of the second phase of the pre-critical period, in which Kant gradually distances himself from dogmatic rationalism, shaping the fundamental concepts of his future critique.

By resorting to the mathematical notion of negative magnitude, Kant will define real opposition as a relationship of opposition in which the opposed predicates do not contradict each other, they are both affirmative, and they constitute equivalent positive principles of existence. Therefore, the characterization "negative" is a conventional designation that does not imply "in any way a particular kind of objects in terms of their internal nature". Negative magnitude is not, therefore, a mere negation or absence, but something positive in itself, which opposes another positive magnitude as something affirmative.

By extending the application of these concepts to the objects of theoretical and practical philosophy, Kant will seek an explanation of the phenomenon of existence outside the field of logical relations, introducing the concept of real principle, which is not subject to the rule of identity and the principle of contradiction.

By questioning the category of causality as a term of possibility of things, the Essay on the Introduction of the Concept of Negative Magnitude in Philosophy (as its full title is) will simultaneously constitute the foundational endeavor of Kantian critique in Leibniz's philosophical system.